Generally, the striking mechanism of music boxes is formed by a vibration plate provided with several strips and a system of activating the strips of the vibration plate; the activation system may take the form of a rotating cylinder or a rotating disc. To fit a watch with such a striking mechanism, it is necessary to reduce the size of the components while taking into account their mechanical strength and while retaining a good sound quality.
Currently, the material of the vibration plate is selected mainly on the basis of manufacturability and resistance to wear and fatigue. Indeed, the strips of the vibration plate are subjected to repeated elastic forces and must therefore be quite resistant in order to have an acceptable lifetime.
Activation energy criteria for the strips must also be taken into account during manufacture of the vibration plate strips. It is known that the shortest strips require higher activation energy than long strips. Short strips are thus subjected to greater elastic forces and must have better resistance to wear and fatigue.
The vibration plates of current striking watches thus have a major drawback since a single material is used to manufacture the vibration plate strips, which means that manufacturers must make a compromise in the selection of material to make strips with acceptable vibration performance for both short strips and long strips. Such a compromise cannot thus achieve optimum results for the reproduction of high and low pitched sounds.